The ground (black) terminal clamp on the battery in my 2007 Mazda-6 has become loose to the point that sometimes the start motor will drain the whole electrical system before it engages. At that point I have to pop the hood and shimmy the clamp to get a connection sufficient to start the car.

I have hit the limit tightening the clamp nut but I can still turn the clamp without much effort. (Maybe this is a consequence of differential metal shrinkage as temperatures have recently been below freezing?)

What is an expedient or proper fix for this? I don't see any corrosion on that terminal. My first inclination was to shim it with some copper wire between the clamp and the terminal, but for all I know that will cause galvanic corrosion.

2 Answers
2

If the clamp is no longer getting tight enough, that could mean the metal is stretched and possibly weak. A dealership would want to replace the whole ground cable with a new, molded on clamp. If there is any slack in the cable, you can buy a replacement clamp and put that on the wire. One way or another, new clamp is the "proper" fix.

In the mean time, there are also "terminal shims" that are made to be a quick fix for this problem at many auto-parts stores:

That's an interesting wire attachment style. I like that the wire would come off at a 90 degree angle. I haven't seen this style in the US - maybe I haven't looked hard enough tho.
– JPhi1618Mar 4 at 17:59

They were the style easily found in the UK - but there are many different styles now - clamps like that with wing nuts for cable terminals or studs and nuts etc
– Solar MikeMar 4 at 18:02

I also like that it has two holding screws on it ... nice add.
– Pᴀᴜʟsᴛᴇʀ2♦Mar 4 at 18:12